Cardiovascular Surgery with Eyes Wide Open

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Abstract

The verification of results in any field has become a fundamental element in many areas of human endeavour. The author believes that this is due to the need to demonstrate to everyone who wishes to collaborate with him, that the goal of the action was effectively reached.
For example, some years ago, quality verification in the car industry led to a strong sales increase by some Far Eastern companies who were very new to the field compared with Western companies, who (in spite of their century-long history of car manufacturing) did not use such control methods. The paradox is that the latter used to be leaders in the production and export of very sophisticated systems for quality control, while the former were their biggest customers.

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In this case, the Latin saying ‘nemo prophoeta in patria’ (no-one is a prophet in his/her own country) might be appropriate. In the medical field, the quality control concept is used constantly in a rather inadvertent way in internal medicine: blood samples are often taken several times a day. The physician needs to know, for example, whether a given dose of insulin produced the desired effect in lowering glycaemia. A quick test for this purpose is conducted using a drop of blood taken from the finger, the result being ready just 60 seconds later.

The waiting time between the execution of a verification test and obtaining the result is another crucial factor with respect to the acceptance of a quality control method – the time before a correction has to be decided, it must be kept short and it is always wise not to wait for clinical manifestation as proof of a possible error.

Intra-operative trans-oesophageal echocardiography is considered mandatory nowadays in order to check a valve repair procedure or to ensure that a prosthesis has been correctly implanted and is functioning well; it is, furthermore, very useful in de-airing after open heart surgery.

For a variety of reasons, cardiac surgeons do not all accept the idea of graft verification in coronary surgery. First of all, many different methods have been proposed during the last 20 years, although the vast majority of them have proved to be faulty, due to an excessive tolerance of parameter values or inconstancy in the results of closely repeated measurements. The reason for this is the influence of too many external factors.

Cardiovascular surgeons are used to putting more trust in the ability of their fingers to detect problems along the grafts than in instruments that measure such feelings objectively: a finger is a sort of transducer capable of transmitting a perception and is far from a measuring instrument.

In addition, surgeons are more prone to use a method that results in a final verdict; the response should be clearly evident on the equipment’s display window.

Finally, surgeons do not like to see evidence displayed when it can still be considered a purely technical mistake; it is now commonly accepted that a graft can be occluded even if perfectly performed.

Once it was established in the mid-1990s that a flow verification instrument was definitely needed in coronary surgery, a couple of smart companies after opportune miniaturisation introduced transit-time technology in clinical practice, until then widely used in the output measurement of oil pits. This is an ultrasound method, based on the transit-time principle, to check the volume of blood flowing through a given section of the graft.

The clinical application very soon demonstrated that, in addition to a simple quantitative measurement (not able per se to depict the situation), qualitative evaluation was possible. This gives surgeons the chance to decide whether a graft needs to be revised or if the probability of staying patent at midterm is low, even in case of a perfect procedure from a surgical point of view.

It should be remembered that this method has not been developed in order to assign blame to the surgeon, but is in order to make him conscious of the situation and allow the patient to receive the best possible treatment. The surgeon will be able to leave the operating theatre secure in the knowledge that he/she has done everything possible.

What then are the real advantages of adopting such a procedure? The first is a clinical one: there is a significantly reduced risk of having to return to the operating theatre soon after the operation, sometimes in an emergency situation, because of an ischaemic complication whose origin is undetermined. In such cases, it is not unusual for the surgeon to find pulsatile grafts but to have no idea about the adequacy of the amount of blood the heart needs. He/she will not be able to focus his/her attention on a particular graft, the solution being to double all the grafts. The operation will take a long time and carry a high risk of morbidity and mortality./>/>/>/>/>/>/>/>/>/>/>/>/>/>/>/>/>/>/>/>

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